“It was just like you were drinking a very strong cleanser,” Chase said. “You could just feel it go down all the way into your stomach.”

Chase said she complained to the restaurant’s manager, who told her they accidentally sold the chemicals-laced batch of milkshakes to at least two other customers. Both those customer’s and Chase’s son, Riley, were taken to the hospital as a precaution, according to Chase.

The manager also told Chase, she said, that the mistake occurred when one employee left a container with chemical cleaner in the sink and then another employee later filled that container with vanilla syrup, thinking the container was clean.

“There's no reason that that should have ever happened,” Chase told ABC News. “They need to be held accountable for what they're doing because they could've cost people their lives.”

In a statement to ABC News, Dairy Queen described the incident as “isolated.”

“This was an accidental and isolated incident,” reads the statement from the Minneapolis-based company. “The employees responsible have been reprimanded. The rest of the staff is getting new training.”

The Dairy Queen incident comes just weeks after a Utah woman was hospitalized after drinking tea tainted with lye at a barbecue restaurant. In that case, an employee mistook degreaser – made up of sodium hydroxide, or lye – for sugar, mixing it into the tea and causing extreme burns to the woman’s throat and mouth, authorities say.